This invention relates to a method of and apparatus for cutting a tunnel in plastic soil. The method and apparatus may, for instance, be used to cut a tunnel for a water line or drainage culvert underneath a roadway.
Various methods of and apparatus for cutting tunnels, including tunnels in plastic soil, are of course known already. Typically, they are quite elaborate, and the apparatus is expensive to manufacture, to maintain, and to use. In addition, many of the known methods can only be practiced safely and efficiently by highly skilled workmen.
Specifically, the most prevalent prior art method of which I am aware incorporates use of an expensive auger drilling rig. The rig requires a large excavation, both in width and length, adjacent the roadway, sidewalk or the like under which the tunnel is being bored. A large auger is driven by a separate motor and large quantities of water are used to help wash the dirt out of the tunnel. This prior method is generally recognized as being wasteful of energy since the separate motor is required. It is laboriously slow and is considered dangerous to operate by many because the large rotating auger must be serviced frequently and workmen are sometimes caught in the rotating mechanism.
Accordingly, a replacement method of and apparatus for cutting tunnels in plastic soil which would be inexpensive to manufacture and to maintain and which could be practiced safely and efficiently by relatively unskilled workmen has long been sought.